Biomolecules and biomarkers in oral cavity: bioassays and immunopathology

The oral mucosa protects the host against invading antigens and pathogenic microorganisms and contains an elaborate immune system and remains in a relative state of health despite the heavy antigen load. The oral barrier is exposed to unique and diverse communities of commensal microbial communities that are known to play immune-stimulatory roles in oral inflammatory diseases. Saliva is secreted from the salivary glands and has multiple functions, including mouth cleaning and protection, antibacterial effects, and digestion. The major protective function of salivary secretions in the oral cavity is through immunological and non-immunological means as well as direct antimicrobial activity. A biomarker is an objectively measured and evaluated indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to therapeutic intervention. With the rapid advancement in salivaomics, saliva is well recognized as a pool of biological markers. Saliva biomarkers include the changes in the biomolecules, such as DNA, RNA and proteins, and the microbial biofilm. There are numerous defense and protective proteins present in the saliva that are involved in oral homeostasis, immunity, and tolerance. This review article attempts to categorize and analyze the various biomolecules and biomarkers in the oral cavity that may be important in pathophysiology.